Related papers: The very fast evolution of Sakurai's object

In 2019, Sgr A* - the supermassive black hole in the Galactic Center - underwent unprecedented flaring activity in the near infrared (NIR), brightening by up to a factor of 100 compared to quiescent values. Here we report ALMA observations…

The dynamics of the core of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy are explored using high-resolution (R~22,500), H-band, near-infrared spectra of over 1,000 giant stars in the central 3 deg^2 of the system, of which 328 are…

There have been great and rapid progresses in the field of $\gamma$-ray bursts (denoted as GRBs) since BeppoSAX and other telescopes discovered their afterglows in 1997. Here, we will first give a brief review on the observational facts of…

Infrared spectra of NGC 7027 and NGC 6543 ranging from 2.4 to 45 micron were obtained with the Short Wavelength Spectrometer on board the Infrared Space Observatory. A first analysis of these spectra, with the aid of photo-ionization…

The Sagittarius B2 (Sgr B2) molecular cloud complex is an X-ray reflection nebula whose total emissions have continued to decrease since 2001 as it reprocesses one or more past energetic outbursts from the supermassive black hole…

We report the discovery of a prominent nonthermal X-ray feature located near the Galactic center that we identify as an energetic pulsar wind nebula. This feature, G359.95-0.04, lies 1 lyr north of Sgr A* (in projection), is comet-like in…

We present near-infrared (IR) spectra of two planetary nebula (PN) candidates in close lines of sight toward the Galactic center (GC) using the Gemini Near-Infrared Spectrograph (GNIRS) at Gemini North. High-resolution images from radio…

The connection between AGB evolution of stellar populations and infrared vs. ultraviolet properties of the parent galaxies is reviewed relying on the updated lookout provided by population-synthesis theory. In particular, planetary-nebula…

We present observations at 610 MHz and 235 MHz using the Giant Metrewave Radio Telescope (GMRT) of the recurrent nova V745 Scorpii which recorded its last outburst on 6 February 2014. This is the second symbiotic recurrent nova whose light…

We present X-ray spectra spanning 18 years of evolution for SN\,1996cr, one of the five nearest SNe detected in the modern era. {\it Chandra} HETG exposures in 2000, 2004, and 2009 allow us to resolve spectrally the velocity profiles of Ne,…

We report on the changing-look nature of the active galactic nucleus (AGN) in the galaxy NGC 4156, as serendipitously discovered thanks to data acquired in 2019 at the Telescopio Nazionale Galileo (TNG) during a students' observing…

The eruption of V4332 Sgr was observed in 1994. During the outburst, the object became extremely red, so it is considered as belonging to luminous red transients of the V838 Mon type. It has recently been suggested that the central object…

We report on recent near-IR observations of V4332 Sgr - the nova-like variable that erupted in 1994. Its rapid, post-outburst evolution to a cool M type giant/supergiant, soon after its outburst, had showed that it was an unusual object…

The results of long-term spectral observations were used to search for changes in planetary nebulae and emission-line stars. Significant increase of excitation degree is found in two objects: M1-6 and M1-11.

We present the stellar and gas kinematics of a sample of 18 nearby late-type spiral galaxies (Hubble types ranging from Sb to Sd), observed with the integral-field spectrograph SAURON at the 4.2-m William Herschel Telescope. SAURON covers…

Late-type stars are the most abundant in the galactic stellar population. These stars, with a similar internal structure to the Sun, are expected to have solar-like atmospheres. Investigating the stellar parameters and chemical abundances…

Five planetary nebulae are known to show hydrogen-poor material near the central star. In the case of A58, this gas was ejected following a late thermal pulse similar to Sakurai's Object. In this paper I will review these five objects. One…

We present multiple epochs of near-IR spectroscopy for a sample of 25 young stars, including T Tauri, Herbig Ae/Be, and FU Ori objects. Using the FSPEC instrument on the Bok 90-inch telescope, we obtained K-band spectra of the BrGamma…

As planetary nebulae evolve, they fade and dissipate into the surrounding interstellar medium making them harder to detect. Modern, advanced amateur equipment can help to uncover this hidden population of ancient 'ghost' planetary nebulae.…

The observation data for artificial celestial body 43096, which had been obtained during 2006-2012 within the framework of international project "The Scientific Network of Optical Instruments for Astrometric and Photometric Observations" -…